Ophthalmic device formed by additive fabrication and method thereof

ABSTRACT

An ophthalmic device is formed by additive fabrication, the optical device having an optical surface with a surface roughness on the order of less than 10 microns. A method is provided for making an ophthalmic device including an optical surface having a surface roughness of less than 10 microns by depositing on a stage in a first relative position a first lamina of particulates having a size less than 10 microns and in select configurations less than two microns and certain configurations less than one micron, and, synergistically stimulating the first lamina of particulates to form a first solidified layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuing application of U.S. Ser. No.12/341,067 filed Dec. 22, 2008 which claims the benefit of U.S.provisional patent application 61/018,009 filed Dec. 31, 2007, thedisclosure of each of which is hereby expressly incorporated byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A “SEQUENCE LISTING”

Not applicable.

TECHNICAL FIELD

This invention relates to the formation of three dimensional objectsusing additive fabrication techniques. More specifically, the inventionrelates to an ophthalmic device which is formed by additive fabricationand a method of making the same.

BACKGROUND OF THE INVENTION

Three dimensional objects can be made rapidly and automatically by rapidprototyping and manufacturing (RP&M). RP&M has proven to be a costeffective technique used to develop prototypes and to manufacturevarious three dimensional products. RP&M is usually classified accordingto specific techniques. Each technique is discussed seriatim below.

A first known technique for making three dimensional objects is byapplying successive layers of unsolidified, fluid-like material to aworking surface. The layers are then selectively solidified according tocross-sectional computer data representing the object. These solidifiedlayers, or laminae, are typically formed of a photo polymer liquidmaterial and solidified via visible or ultraviolet electromagneticradiation from a laser. More specifically, his technique involvesapplying liquid material to areas which will, and which will not, bepart of the finished three dimensional object. The radiation is thenused to solidify only those areas that are part of the three dimensionalobject. Often referred to as stereolithography, this technique is knownand disclosed in several patents and patent applications, for example,U.S. Pat. No. 4,575,330 to Hull. Similarly, layers of a powered materialcan be selectively solidified by depositing a chemical binder materialthereon.

Another type of RP&M is selective deposition modeling, which createsthree dimensional objects by selectively depositing a liquid likematerial onto a working surface in patterns that become part of asolidified layer. That is, a layer is deposited based on cross-sectionaldata that represents slices of the three-dimensional object and is thensolidified. A subsequent layer is added and solidified to the previouslyformed solidified layer. By repeating these steps, a three dimensionalobject is built lamina-by-lamina. With this technique, the liquidmaterial is flowable but only deposited in the regions that form thethree dimensional object.

Yet a third technique used for RP&M is laminated object manufacturing.With this method, three dimensional objects are formed by stackingsheets of material together wherein each sheet is adhered to another.The stacked sheets are then selectively cut in a particular order toform the desired three dimensional object, according to computer datarepresenting the cross-sectional slices of the three dimensional object.

While these techniques have allowed for the manufacturing of manydifferent types of three dimensional objects, they have not been usefulin the creation of ophthalmic devices. Heretofore, the RP&M techniquesdescribed above have only achieved surface variations of the object ofapproximately 50 microns or greater.

SUMMARY OF THE INVENTION

Ophthalmic devices require a surface variation or roughness in theoptical surface that is less than approximately 10 microns and typicallyless than two microns and preferably less than one micron. An extremetopography of the optical surface as in the prior art, such as on theorder of 50 microns, causes discrepancies in the refractive indices as aresult of the “hills” and “valleys” in the optical surface.

It is therefore, desirable to provide an ophthalmic device usingadditive formation techniques, wherein the ophthalmic device has asurface variation or roughness on the order of less than 10 microns andin select configurations less than two microns and in certainconfigurations less than one micron (submicron).

The present disclosure broadly comprises an ophthalmic device having anoptical surface formed by additive fabrication, wherein the opticalsurface has a surface roughness of less than 10 microns, and in selectconfigurations less than 2 microns, and preferably less than one micron.

The present disclosure further comprises a method of making anophthalmic device having an optical surface by depositing on a stage ina first relative position a first lamina of particulates having a sizeless than 10 microns and in select configurations less than 2 micronsand in certain configurations less than one micron, and synergisticallystimulating the first lamina of particulates to form a first solidifiedlayer, a portion of the layer forming a portion of the optical surface.

The present disclosure further comprises an ophthalmic device and methodof making such an ophthalmic device having an optical surface bydepositing on a stage in a first relative position a first lamina havinga thickness of less than 10 microns and in select configurations lessthan 2 microns and in certain configurations less than one micron, and,synergistically stimulating the first lamina of particulates to form afirst solidified layer, the layer forming at least a portion of theoptical surface. The resulting optical surface can have a surfaceroughness less than 10 microns and in select configurations less than 2microns and in certain configurations less than one micron.

The present disclosure also comprises a method of forming an ophthalmicdevice comprising depositing by additive fabrication a plurality ofbonded laminae to define an optical surface, the lamina having athickness of less than 10 microns, and in select configurations lessthan 2 microns and in certain configurations less than one micron.

An object of the disclosure is to provide an ophthalmic device having anoptical surface with surface roughness less than 10 microns, and inselect configurations less than 2 microns and in certain configurationsless than one micron, the optical surface formed by additivefabrication.

It is another object of the disclosure to provide an ophthalmic devicehaving an optical surface formed from solidified layers of particulates,the particles having a size less than 10 microns, and in selectconfigurations less than 2 microns and in certain configurations lessthan one micron.

It is further object of the invention to provide a method of making anophthalmic device by additive fabrication, wherein the ophthalmic devicehas an optical surface with a surface roughness of less than 10 microns,and in select configurations less than 2 microns and in certainconfigurations less than one micron.

The novel aspects of the invention are set forth with particularity inthe appended claims. The invention itself, together with further objectsand advantages thereof, may be more readily comprehended by reference tothe following detailed description of a presently preferred embodimentof the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a schematic diagram of main functional components of anadditive fabrication apparatus;

FIG. 2 is a perspective view of the main functional components of theadditive fabrication apparatus;

FIG. 3 is a flow chart diagram illustrating the build-up of theophthalmic device of FIG. 1.

FIG. 4 is a perspective view of laminae of an ophthalmic device.

FIG. 5 is a partial cross-sectional view of an ophthalmic device.

DETAILED DESCRIPTION OF THE INVENTION

At the outset, it should be appreciated that the use of the samereference number throughout the several figures designates a like orsimilar element.

Referring now to the Figures, FIGS. 1 and 2 depict a schematicrepresentation of an additive fabrication apparatus 10 for use in makingophthalmic devices 12. In one configuration, the additive fabricationapparatus 10 includes cross-sectional computer data 14 of athree-dimensional object which is transferred to a computer systemcomprising a machine controller 16. The cross-sectional computer data 14can be created in a typical computer aided design (CAD) system, whereina user creates an ophthalmic device which can be saved as a data filecontaining coordinate information corresponding to cross-sectionalslices of the ophthalmic device 12. Such method and apparatus forslicing a three-dimensional object is described in U.S. Pat. No.5,854,748 to Snead et al., which is hereby incorporated by reference.This data file of the ophthalmic device 12 is formed into coded binaryinformation that is transferred to a machine controller 16.

The machine controller 16 communicates with a dispensing head 18 and astage 20 arranged to support the ophthalmic device 12 being formed. Thedispensing head 18 is connected to a dispensing head positioner 22,wherein the dispensing head 18 is selectively moveable in the X- andY-axes by commands from the machine controller 16. In an embodiment ofthe invention, the dispensing head 18 is also selectively moveable inthe Z-axis. More preferably, the dispensing head 18 is moveable in anydirection according to instructions received from the machine controller16.

The dispensing head 18 undergoes back and forth movements andaccelerations, similar to commercial print head configurations used intypical three-dimensional modeling systems. The dispensing head 18 maybe any suitable ejection head having an ejection nozzle 24 for emittingsmall mass particulates or droplets of particulate material. In oneembodiment the dispensing head 18 ejects droplets that are less than 10microns and in select configurations less than two microns and certainconfigurations less than one micron (submicron) in size. In oneembodiment, the dispensing head 18 comprises an array of dispensing pins26 arranged in the nozzle 24 which dispense a plurality of particulatesaccording to the instructions received from the machine controller 16.Each dispensing pin 26 is individually controllable such thatparticulates may be dispensed from some, but not all of the pins 26,according to the machine controller 16 instructions. Any suitable numberof dispensing pins 26 may be utilized. Further, the pins 26 may beconfigured according to any preferred arrangement. The dispensing head18 can be configured similar to the droplet dispenser disclosed in U.S.Pat. No. 6,808,683 to Gilbert, which is hereby incorporated byreference. Alternatively, the nozzle 24 may include orifices 28 capableof dispensing micron or submicron sized particulates as discussed inmore detail below, wherein any optimal number of orifices 28 can beselected and arranged in a desired configuration.

In an embodiment, the particulates are formed from unsolidified,flowable material which is curable, for example, thermoplastic,monomeric or wax-like material. The ejected material for forming theophthalmic device can be as set forth in the following US patents, eachof which is hereby expressly incorporated by reference, U.S. Pat. No.7,297,160 entitled High refractive-index, hydrophilic,arylsiloxy-containing macromonomers and polymers, and ophthalmic devicescomprising such polymers; U.S. Pat. No. 7,279,538 entitledAromatic-based polysiloxane prepolymers and ophthalmic devices producedtherefrom; U.S. Pat. No. 7,198,639 entitled Polysilsesquioxanecontaining polymeric compositions; U.S. Pat. No. 7,176,268 entitledPrepolymers for improved surface modification of contact lenses; U.S.Pat. No. 7,169,874 entitled High refractive index polymeric siloxysilanecompositions; U.S. Pat. No. 7,138,440 entitled High refractive indexpolymeric siloxysilane compositions; U.S. Pat. No. 7,132,494 entitledHigh refractive index aromatic-based silyl monomers; U.S. Pat. No.7,132,493 entitled High refractive index aromatic-based prepolymerprecursors; U.S. Pat. No. 7,132,492 entitled High refractive indexaromatic-based prepolymer precursors; U.S. Pat. No. 7,101,949 entitledHigh refractive index polymeric siloxysilane compositions; U.S. Pat. No.7,091,299 entitled High refractive index polymeric siloxysilanecompositions; U.S. Pat. No. 7,009,024 entitled High refractive indexaromatic-based siloxane difunctional macromonomers; U.S. Pat. No.7,009,023 entitled High refractive index aromatic-based siloxanedifunctional macromonomers; U.S. Pat. No. 7,005,494 entitled Highrefractive index aromatic-based siloxane monofunctional macromonomers;U.S. Pat. No. 6,992,162 entitled High refractive index aromatic-basedsiloxane monofunctional macromonomers; U.S. Pat. No. 6,989,430 entitledHigh refractive index aromatic-based siloxane monofunctionalmacromonomers; U.S. Pat. No. 6,956,087 entitled High refractive indexpolysiloxane prepolymers; U.S. Pat. No. 6,951,914 entitled Highrefractive index aromatic-based prepolymer precursors; U.S. Pat. No.6,908,978 entitled High refractive index polymeric siloxysilanecompositions; U.S. Pat. No. 6,906,162 entitled High refractive indexaromatic-based siloxane monofunctional macromonomers; U.S. Pat. No.6,891,010 entitled Silicone hydrogels based on vinyl carbonate endcappedfluorinated side chain polysiloxanes; U.S. Pat. No. 6,881,809 entitledHigh refractive index aromatic-based silyl monomers; U.S. Pat. No.6,881,808 entitled High refractive index aromatic-based siloxanedifunctional macromonomers; U.S. Pat. No. 6,864,342 entitled Highrefractive index aromatic-based prepolymers and U.S. Pat. No. 6,864,341entitled High refractive index aromatic-based prepolymer precursors.

In an alternative embodiment, the particulates are a chemical binderwhich adhere material in a powdered form. Of course, if a chemicalbinder and particulate embodiment is used, the refractive index of eachmaterial should be approximately the same, and more preferablyidentical.

The dispensing head 18 utilizing orifices 28 capable of dispensingmicron or submicron sized particulates, preferably includes an orificeplate 32 mounted on the dispensing portion of the dispensing head 18.Each orifice 28 is preferably equipped with a piezoelectric element thatcauses a pressure wave to propagate through the material when anelectronic firing pulse is supplied to the element. The pressure wavecauses the particulate material to be released from the orifice 28. Themachine controller 16 determines the rate and timing of the firing pulseapplied to each individual orifice 28.

To accurately build the ophthalmic device 12, the particulates dispensedfrom the dispensing head 18 need to be accurately placed in a desiredlocation so that the particulate layers, or laminae, can be built-upvertically. The desired location is determined from the computer dataproviding a data map or pixel locations that identify the desiredlocation. To obtain such desired location, the dispensing head 18 mustbe directed to a predetermined dispensing position by the dispensinghead positioner 22. Additionally, the stage 20 for supporting theophthalmic device 12 can be directed to a predetermined stage positionby a stage positioner 30, wherein the stage position is related to thepredetermined dispensing position at the particular time of firing ofthe material through the ejection nozzle 24. The stage 20, connected tothe stage positioner 30, is selectively moveable in the X and Y-axes bycommands from the machine controller 16. That is, in an embodiment ofthe invention, the stage 20 is moveable, horizontally andperpendicularly to the ground. In an embodiment of the invention, thestage 20 is also selectively moveable in the Z-axis. Although the stage20 is preferably moveable along at least the Y-axis, movement of thestage 20 is not required at all since the dispensing head 18 can bemoveable in all directions in a relative manner to the stage 20.

The machine controller 16 selectively moves the stage 20 with micron orsubmicron motion control. Obtaining micron or submicron positioning of astage in a high resolution system is well known in the art and can beperformed by commercially available or custom developed systems such asthe DynamYX and the Mat350 submicron positioning systems of KensingtonLaboratories of Richmond, Calif., the nano resolution linear stages ofALIO Industries of Wheat Ridge, Colo., the motion controllers and theNanoStepper of Baldor Electric Company of Fort Smith, Ark., themulti-axes, sub-micron positioner described in U.S. Pat. No. 6,888,289to Heilig et al. which is hereby incorporated by reference, and themotion controllers of Galli Motion Control, Inc.

In one embodiment, raster scanning is used to position the dispensinghead 18 having either pins 26 or orifices 28 at the desired firinglocations. That is, the printing process for each lamina is accomplishedby a series of relative movements between the dispensing head 18 and thedesired firing locations. Printing typically occurs as the dispensinghead 18 relatively moves in a main scanning direction. This is followedby a typically smaller increment of movement in a secondary scanningdirection while no dispensing occurs, which in turn is followed by areverse scan in the main scanning direction in which dispensing againoccurs. The process of altering main scans and secondary scans occursrepeatedly until the laminae are completely deposited.

Alternative embodiments may perform small secondary scanning movementswhile main scanning occurs. Because of the typically large difference innet scanning speed along the main and secondary directions, such analternative still results in deposition along scanning lines which arenearly parallel to the main scanning direction and perpendicular to thesecondary scanning direction. Further alternative preferred embodimentsmay utilize vector scanning techniques or a combination of vectorscanning and raster scanning techniques.

The liquid particulates, immediately after being dispensed from thedispensing head 18, have an elongated shape, compared to the width ofthe particulates. The ratio of particulate length to width can bedefined as the aspect ratio of the particulate. The aspect ratio ofthese particulates becomes smaller as the particulates travel away fromthe dispensing head 18. Nonetheless, the spacing between the dispensinghead 18 and stage 20 is minimized to avoid inaccurate deposition, sinceinaccuracies increase with the distance the particulates travel.

The additive fabrication apparatus 10 further includes a synergisticstimulator 34 that causes the particulates dispensed from the dispensinghead 22 to selectively harden. In one embodiment, the synergisticstimulator 34 is a ultra-violet (UV) laser which is capable of curing aliquid material. Alternatively, the synergistic stimulator 34 can beinfrared (IR) radiation from a carbon dioxide laser, which canselectively harden a sinterable powered. Further, the synergisticstimulator 34 can be a chemical binder which can adhere particulatepowder upon selective application of the chemical binder. It should beappreciated by those having ordinary skill in the art that, thesynergistic stimulation can be applied after the liquid material isfully deposited on the stage 20, wherein the synergistic stimulationdefines areas that will be part of the ophthalmic device 12.Alternatively, the synergistic stimulation can be appliedlamina-by-lamina, wherein material is only deposited in areas that formthe ophthalmic device 12. Preferably, however, the synergisticstimulation is applied lamina-by-lamina, wherein a layer of material isprinted and cured before a next layer is built.

For example, the additive fabrication apparatus 10 builds an ophthalmicdevice 12 lamina-by-lamina to form an ophthalmic device 12 having anoptical surface 36 shown in FIG. 4, wherein the lamina have a thicknessless than 10 microns and in select configurations less than two micronsand certain configurations less than one micron (submicron) in size.“Ophthalmic device” is meant to include, but is not limited to, a devicesuitable for placement in the eye, for example, an intraocular lens(IOL) or a corrective, therapeutic or cosmetic contact lens. The opticalsurface 36 of the ophthalmic device 12 has a surface roughness of lessthan 10 microns and in select configurations less than two microns andcertain configurations less than one micron (submicron) in size. Thatis, the surface topography of the ophthalmic device 12 can have asurface roughness of less than one micron.

As shown in the figures, to build an ophthalmic device, a desired numberof laminae is determined (step 102) based on information obtained fromthe CAD data (step 100). The stage 20 and/or the dispensing head 18 aredirected to move by the machine controller 16 (step 104) and a lamina isdispensed (step 106). When the first lamina is being dispensed, thenozzle 24 is arranged in a predetermined position in relation to thestage 20. The last-built lamina is positioned proximate to the nozzle 24allowing the next to-be-built lamina to be placed in a registered mannerwith the first lamina. The nozzle 24 undergoes back and forth movementsand accelerations until a new lamina is deposited on the last-builtlamina. During the translation of the dispensing head nozzle 24, theparticulates are ejected therefrom. A sacrificial material 38 can beused to support the laminae during the printing process. That is, toprevent the laminae from collapsing during formation, a wax-likematerial can be simultaneously or contemporaneously ejected from some ofthe orifices 28 or pins 26 of the nozzle 24.

Once a lamina is formed, the synergistic stimulator 34 selectivelyhardens the lamina (step 108). In a preferred embodiment, UV radiationis used to cure the lamina. As discussed above, however, othersynergistic stimulators can be used. For example, the synergisticstimulator 34 can be a chemical binder ejected from the dispensing head18 to adhere a powdered material. The machine controller 16 determineswhether the desired laminae number has been reached upon completion ofthe lamina deposit (step 110). If not, the next lamina is formed in aregistered manner with respect to the last-built lamina, wherein thedispensing head 18 and/or stage 20 are translated to align thedispensing head 18 with respect to the last built lamina. This processof lamina depositing and synergistic stimulation is repeated until thedesired number of laminae has been completed (step 112).

The ophthalmic device 12 oriented in a convex position can be built bydepositing a first lamina ring having a predetermined circumference ofparticulate material and then applying additional, progressively smallerlamina rings of particulate material to the last-build laminae.Sacrificial material 38 can be deposited in the enclosed regions tosupport the laminae. The ophthalmic device 12 oriented in a concaveposition can be created by depositing progressively larger lamina ringshaving a predetermined circumference on the last-built lamina, whereinsacrificial material 38 is deposited on the outer surface of the device12 to support the layers. It should be appreciated that sacrificialmaterial 38 serves several purposes. Specifically, the sacrificialmaterial 38 forms a working surface on which to build object lamina andeven successive support lamina. Further, the sacrificial material 38 iseasily removable from the optical surface 36 it supports. Also, whenremoved, only a minimal amount of damage to the optical surface 36 isincurred, which can be corrected by heat annealing as described in moredetail below. To optimize building speed, vertical accumulation of thesacrificial material 38 is important and, as such, it is desirable tohave sacrificial material 38 built-up at approximately the same rate asthe ophthalmic device 12. Specifically, it is preferred that thevertical accumulation of the sacrificial material 38 accumulates atleast as fast as the laminae defining the optical surface 36.

It should be apparent that, after the formation of the ophthalmic device12 using the additive fabrication method described above, an additionaloptional step can be taken to assist in forming the desired micron orsubmicron optical surface roughness. That is, the ophthalmic device 12can be heat annealed, thereby providing a resultant optical surface 36having a surface roughness of one micron or less than one micron. Thisstep is particularly useful when the optical surface 36 is damagedduring the removal of sacrificial material 38.

The surface roughness of the ophthalmic device is a measure of amplitudeof surface variations based on the vertical deviations of the roughnessprofile from a mean line. For example, Ra is the arithmetic average ofthe absolute values. Thus, in one configuration the surface roughnesscan be defined as having an Ra of less than 10 microns and in selectconfigurations less than two microns and certain configurations lessthan one micron (submicron). Alternatively, the surface roughness can bedefined in terms of RMS (root mean square) as less than 10 microns andin select configurations less than two microns and certainconfigurations less than one micron (submicron). Surface finish, surfaceroughness, is usually specified based on the ASME Y14.36M-1996 standard.

There has thus been described an ophthalmic device formed by additivefabrication having an optical surface with an optical surface having asurface roughness of less than 10 microns and in select configurationsless than two microns and certain configurations less than one micron(submicron) and a method of making the same. Those skilled in the artwill recognize that modifications may be made in the method andapparatus described herein without departing from the true spirit andscope of the invention which accordingly are intended to be limitedsolely by the appended claims.

The invention claimed is:
 1. An ophthalmic device having an optical surface and a plurality of additive fabrication lamina, wherein one of the plurality of additive fabrication lamina forms at least a portion of the optical surface.
 2. The ophthalmic device of claim 1 wherein each of the plurality of additive fabrication lamina is a UV curable material.
 3. The ophthalmic device of claim 1 wherein each of the plurality of additive fabrication lamina is an IR curable material.
 4. The ophthalmic device of claim 1 further comprising a chemical binder.
 5. The ophthalmic device of claim 1 further comprising a removable sacrificial material arranged to support the optical surface.
 6. The ophthalmic device of claim 5 wherein the removable sacrificial material is a wax.
 7. The ophthalmic device of claim 1 wherein each of the plurality of additive fabrication lamina has a thickness of less than 1 micron.
 8. The ophthalmic device of claim 1 wherein the ophthalmic device is a lens.
 9. The ophthalmic device of claim 1 wherein the ophthalmic device is a corrective lens.
 10. The ophthalmic device of claim 1 wherein the plurality of additive fabrication lamina are printed.
 11. A corrective lens consisting of a plurality of printed layers, wherein at least one of the plurality of printed layers forms at least a portion of an optical surface of the corrective lens.
 12. An ophthalmic device having an optical surface, the ophthalmic device consisting of a plurality of additive fabrication lamina, wherein one of the plurality of additive fabrication lamina forms at least a portion of the optical surface. 